IRON    ORES    OF    THE    WEST.  197 
where  they  lie  both  parallel  and  transverse,  mainly  the  former,  to  the  bedding  of  Carbon- 
iferous and  Silurian  limestones  and  shales  dipping  westward  into  the  mountain.  These 
rocks  are  underlain  by  a  thin  layer  of  Cambrian  quartzite  and  this  in  turn  by  the  "Sawatch  " 
granite,  which  appears  on  the  lower  parts  of  the  sleep  erosion  slopes  of  the  mountain.  The 
overlying  rocks  are  fine-grained  diori  es  of  recent  age.  The  ore  probably  occurs  in  more 
than  one  layer,  but  how  many  the  explorations  do  not  show.  At  Taylors  Peak  a  vertical 
pit  40  feet  deep  has  been  sunk  in  the  ore.  The  dip  of  the  ore  while  probably  westward,  was 
not  determined  at  the  pit,  so  that  the  thickness  of  the  belt  <  an  nol  be  est  imated.  The  ore 
is  here  mainly  a  magnetite  containing  iron  sulphide  and  chlorite.  A  the  surface  it  is 
oxidized  to  limonite,  which  appears  abundantly  on  the  lower  s.opes.  A  single  specimen 
collected  here  to  show  the  nature  of  the  ore  carries  48.36  per  cent  of  iron,  0.007  per  cent 
phosphorus,  and  5.88  per  cent  sulphur,  but  the  average  of  the  hole  is  said  to  show  better- 
grade  ore.  A  tunnel  is  now  being  driven  into  the  underlying  blue  limestone  in  search  for 
silver  and  lead. 
Like  the  ore  on  the  northwest  side  of  the  divide,  the  concentration  of  this  ore  under  the 
influence  of  igneous  rocks  is  apparent.  It  is  said  to  be  continuous  with  t  he  ore  on  the  nor,  h- 
west  side;  indeed,  ore  can  be  seen  extending  to  the  divide  on  each  side.  This  would  give 
the  belt  an  approximate  length  of  a  mile,  with  a  maximum  width  of  122  feet,  as  shown  in 
one  of  the  tunnels  on  the  northwest  side  of  the  divide,  but  with  an  average  width  probably 
much  less.     The  depth  is  unknown. 
A  visit  was  made  to  the  iron-ore  deposit  about-  three-fourths  of  a  mile  northeast  of  the 
village  of  White  Pine,  Gunnison  County.  It  occurs  on  the  east  slope  of  the  valley,  on  a  spur 
of  the  Saguache  Mountains.  The  ridge  has  a  granite  core  and  carries  on  its  slope  Cambro- 
Silurian  quartzite  and  limestone,  dipping  westward  down  the  slope-.  The  ore  is  at  the  <  mi- 
tact  of  the  limestone  and  quartzite,  apparently  replacing  both.  The  dip  of  the  ore  seems 
to  be  parallel  to  the  slope,  although  locally  it  dips  into  the  hill,  perhaps  as  a  result  of  creep. 
Six  tunnels  crossing  the  ore  were  examined.  One  tunnel  showed  two  seams  14  and  75  U^c\ 
in  width.  The  ore  was  not  followed  along  the  strike  for  any  great  distance,  but  it  is  said 
to  extend  to  Marshall  Pass,  several  miles  away.  The  ore  is  crystalline  magnetite  and  hema- 
tite containing  epidote,  garnet,  and  some  iron  sulphide1,  but  not  in  large  amount.  At  the 
surface  it  is  altered  to  limonite,  hematite,  and  clay.  In  some  of  it  fragmental  quartz  grains 
may  be  seen.  A  sample  analyzed  by  Chauvenet  averaged  58.75  per  cent  in  iron  and  0.04 
per  cent  in  phosphorus.  An  average  analysis  of  ten  samples  published  by  Birkinbine  gives 
59.32  per  cent  in  iron,  0.036  per  cent  in  phosphorus,  and  7.9  per  cent  in  silica. 
Iron  ores  were  examined  along  the  north  side  of  Cebolla  Creek,  about  15  miles  south  of 
Iola  station,  on  the  Denver  and  Rio  Grande  Railroad.  Here  there  is  an  amphitheater  of 
granite  opening  out  to  the  southeast  diagonally  a<  ross  the  <  reek,  partly  in<  losing  quartzite 
and  above  this  limestone,  iron  carbonate,  and  iron  ore.  On  the  northwest  trachyte  flows 
cap  both  the  granite  and  the  sedimentary  rocks.  The  limestone,  iron  carbonate,  and  iron 
ores  appear  principally  in  three  small  east-west  hills  arranged  en  t'c  helon  north  of  the  creek. 
The  limestone  may  be  seen  to  grade  up  into  iron  carbonate  or  ferriferous  limestone  or  dolo- 
mite, which  const iti.' es  most  of  the  central  hill,  the  west  end  of  the  western  hill,  and  an 
unknown  r.art  of  the  eastern  hid.  This  iron  carbonate  varies  from  fine  to  coarse  grained 
and  is  .intimately  interbanded  with  magnetite  and  hematite,  suggesting  contemporaneous 
origin.  Whether  the  iron  carbonate  and  its  associated  iron  oxide  consists  of  an  original 
sedimentary  formation  conformable  with  the  limestone  below  or  is  a  result  of  subsequent 
alteration  aided  by  igneous  agencies  was  not  determined.  In  favor  of  the  former  is  its  fine 
grain  in  places  and  apparent  conformability  with  the  limestone.  In  favor  of  the  latter  is 
its  local  coarsety  crystallized  character  and  the  occurrence  of  this  coarser  carbonate  in  dis- 
tinct veins.  At  the  surface  the  carbonate  is  altered  to  limonite  and  clay,  with  the  develop- 
ment and  introduction  of  chlorite,  chalcedony,  and  manganese  oxide.  One  specimen  here 
taken  runs  45.92  per  cent-  in  manganese.  This  alteration  is  confined  principally  to  the 
localities  adjacent  to  the  overlying  trachyte  capping,  especially  near  the  east  ends  of  the 
